Grease composition



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The present invention relates to grease compositions exhibiting superior characteristics as a result of the incorporation of a fatty amine silicate.

The object of my invention is to provide an adjuvant for alkaline metal, soap-thickened lubricating greases which will enhance the bleeding, pressure viscosity, yield, mechanical stability and storage stability characteristics. Alkaline metal, i.e. alkali metal and alkaline earth metal, soapthickened greases are well known. The present invention is based upon the discovery that the incorporation of a fatty amine silicate into greases of this type materially increases the pressure viscosities of the greases at 210 F. without disturbing low temperature viscosity requirements, reduces bleeding, increases yield, and aids in reclaiming out-of-grade lubricating greases without undue manufacturing procedures.

The grease compositions of the present invention include a lubricating oil thickened to grease consistency with a gelling agent, erg. an alkaline metal, i.e. alkali or alkaline earth metal, soap and physical characteristic enhancing amounts of a fatty amine silicate. The amounts of lubricating oil and soap components employed in these grease compositions are conventional and will depend upon the properties desired in the finished grease. However, generally at least about 50 weight percent of a synthetic, e.g. di(2-ethylhexyl) sebacate, di-cellosolve phthalate and the halogenated bi-phenyls, e.g. trichlorodiphenyl or mineral lubricating oil can be employed in conjunction with a minor amount, generally from about 540 weight percent, of the soap component. Suitable soap components include the sodium, calcium, sodium-calcium, and lithium soaps derived from fatty acids of about 12 to 20 carbon atoms, their glycerides and their combination. The grease may also have therein a metal salt of a short chain fatty acid as in the so-called complex greases.

The fatty amine silicate compound contains a fatty acid radical and an amine radical and is preferably a mono fatty acid derivative of a polyamine silicate salt. One such fatty amine silicate is commercially available from The Nopco Chemical Company as Metasap 248," identified as monostearoyl tetraethylene pentamine silicate, obtained by reaction of an excess of sodium silicate (Na O:3.22SiO in water solution with an acetate salt of a hydrogenated tallow fatty acid monarnide (produced by reaction of tetraethylene pentamine with the tallow acids and subsequent addition of glacial acetic acid) at 70-80 C., and addition of hydrochloric acid to a pH of about 7.8. The amount of the fatty amine silicate employed in my compositions is generally from about 0.25% to 20% and preferably from about 0.5 to 3% but optimally about 1%.

These grease compositions of the present invention can be prepared by known procedures. For example, the soaps can be preformed and then incorporated in the oil. Preferably, however, the soaps are prepared in situ in the atent presence of a portionor all of the oil of the final composition. Final temperatures of about 250 to 425 F. are usually used with maximum processing temperature of about 340 to 350 F. being preferred. A particularly satisfactory procedure comprisesadding saponifiables and starting oil to a kettle and heating until substantially complete solution is effected. A hot slurry of lithium or other metal hydroxide is then added and the mixture is agitated vigorously While the temperature is raised gradually to evaporate water. During saponification and dehydration, quantities of the oil advantageously are added to limit foaming and maintain the mixture in'at least a semifluid state. After dehydration, it is advantageous to raise the temperature of the mass to about 300 to 350 F. for periods up to about 1 or 2 hours. At the end of this period, the grease is permitted to cool, or alternatively, further quantities of oil, as necessary or desired, can be added to facilitate cooling. The addition of the fatty amine silicate as well as other additives such as oxidation inhibitors and the like can be added and the grease can also be milled in'the usual manner.

The invention may be further illustrated with reference to the following specific examples. A composition, composition A, set forth in Table I, was prepared by forming.

in a portion of the mineral oil base the soap in situ from hydrogenated castor oil and an aqueous solution of lithium hydroxide monohydrate The composition was dehydrated at a maximum processing temperature of 350 F. and after cooling to about 170 F. was processed through a colloid mill set at 0.005 inch clearance and dcareated before packaging.

A second composition, composition B, was preparedfollowing a procedure similar to that for the preparation of composition A above with the exception that the Metasap 248 was incorporated into the grease before the grease was milled. This composition is also set forth in Table I. The physical properties for each of these compositions are given in Table II and demonstrate the superior properties, e.g. anti-bleeding and improved pressure viscosity relationship of grease containing the Metasap 248.

TABLE I No. I grade of lithium hydrogenated castor oil soap grease Composl- Composition A, tion 13, percent by percent by wt. wt.

Formula:

Vopcolene (Hydrogenated Castor 011).. 8. 049 8. 049 Ntofat )16-54 (Palmltic-Stea1'le Acid Eu- 0. 435 0.435

ee 10 L1OH.H O 1. 212 1. 212 Base Oil 89. 791 89. 791 Ortholeum 300 (Oxidation Inhibitor) 0. 513 0. 513 Composition:

Lithium Vopocolene 75 Soap 7.97 7. 97 Lithium N eofat 16-54 8094).... 0.45 0. 45 Base Oil 91.06 91. 00 Ortholeum 300 0. 52 0. 52 Stabilizing Agent- Base Grease 100 99. 0 Metasap 248 None 1. 0

3 TABLE 11 Physical properties Composition A Composition B No. 1 Grade of No. 1 Grade of Lithium Hy- Lithium Hydrogenated drogenated Castor Oil Castor Oil Soap Grease Soap Grease +1% Metasap Penetration Unworked at 77 F 349 336 ASTM Penetration at 77 F 345 330 ASTM Dropping Point, F 378 378 Accelerated Bleeding (AAR 24 hrs. 210 F.) percent 8.5 1,2 Corrosion 24 hrs. at RT-Oooper Nil All Pressure Viscosity (850 Sec. 1):

SUS Viscosity at- 345 330 342 326 10,000 Strokes. 341 326 100,000 Strokes 341 326 Storage Stability, Percent Bleeding, 4

months 1. 2 Trace It is well known to those skilled in the art, that calcium and sodium greases are inferior to lithium greases in that they tend to soften upon storage. A plant batch of a calcium soap type grease which did not remain in grade during storage was treated with one percent Metasap 248 by heating to 210 F. and stirring. An increase of thirty penetration points over the as-stored grease was observed in the Metasap 248 treated grease which brought the processed grease into grade. A temperature of only 210 F. and limited processing time was needed to reclaim the grease. These laboratory investigations indicate that Metasap 248 aids materially in reducing out-of-grade grease reclaiming time. It was also noticed that the addition of Metasap 248 decreased the bleeding tendencies of this product over the same product that was manufactured in grade.

Thus it is shown that Metasap 248 can be used as an inexpensive means of reclaiming out-of-grade and unstable greases. Further investigations of the properties of Meta sap 248 has indicated that it is also effective in sodium, calcium, sodium-calcium, and lithium greases normally prepared by the procedures set forth above.

Although my invention has been described with a certain degree of particularity, it is to be understood that I do not wish to be limited to the details set forth, but my invention is to be given the full scope of the appended claims. V

I claim:

1. A grease composition consisting essentially of a lubricating oil thickened to a grease consistency with a soap selected from the group consisting of alkali metal and alkaline earth metal fatty acid soaps and from about 0.25 to 20% of monostearoyl tetraethylene pentamine silicate.

2. A grease composition consisting essentially of at least of a lubricating oil, 5 to 40% of a soap selected from the group consisting of alkali metal and alkaline earth metal fatty acid soaps and from about 0.5 to 3% of monostearoyl tctraethylene pentamine silicate.

3. A grease composition consisting essentially of at least 50% of a lubricating oil, 5 to 40% of a soap selected from the group consisting of alkali metal and alkaline earth metal fatty acid soaps and about 1% of monostearoyl tctraethylene pentamine silicate.

4. A process for lubricating metal surfaces comprising coating the metal surfaces with a grease composition consisting essentially of a lubricating oil thickened to grease consistency with a soap selected from the group consisting of alkali metal and alkaline earth metal fatty acid soaps, and 0.25 to 20% monostearoyl tctraethylene pentamine silicate.

References Cited in the file of this patent UNITED STATES PATENTS 2,450,254 Puryear et a1 Sept. 28, 1948 2,642,397 Morway et a1 June 16: 1953 FOREIGN PATENTS 215,120 Australia May 26, 1958 

1. A GREASE COMPOSITION CONSISTING ESSENTIALLY OF A LUBRICATING OIL THICKNENED TO A GREASE CONSISTENCY WITH A SOAP SELECTED FROM THE GROUP CONSISTING OF ALKALI METAL AND ALKALINE EARTH METAL FATTY ACID SOAPS AND FROM ABOUT 0.25 TO 20% OF MONOSTEAROYL TETRAETHYLENE PENTAMINE SILICATE. 